Malaria is one of the major scourges in tropical countries and is responsible for significant mortality in its severe form, particularly among children in Africa. In 2022, the WHO estimated 608,000 malaria-related deaths, with 80% occurring in children living in sub-Saharan Africa [1] . In the Republic of Congo, according to national data, malaria is the leading cause of death, accounting for 28% of cases [2] . MOYEN and collaborators reported a case-fatality rate of 26.3% in Brazzaville hospitals [3] . Reducing the burden of malaria is a public health priority and is at the heart of Millenium Development Goals (MDG) 3 [4] . This involves specific preventive measures, rapid and accurate diagnosis of cases and effective treatment.

The diagnosis of severe malaria relies on clinical and biological criteria defined by the WHO in 2015 [5] . The identification of one of the Plasmodium species recognized as responsible for severe forms, (primarily Plasmodium falciparum in Congo), is essential for diagnosis via microscopy. However, microscopy methods (thick blood smear and blood films for Plasmodium detection), which form the basis of diagnosis, can be falsely negative in certain situations, such as in children who are incompletely treated, due to parasitic density falling below the detection threshold. In such cases, it becomes difficult to differentiate between poorly treated severe malaria and other conditions with similar symptoms. It is common practice to initiate presumptive antimalarial treatment in such situations.

However, this practice, which is contrary to the WHO recommendation to treat malaria cases with biological evidence, is not without its disadvantages [6] ; not only does it delay the diagnosis and management of diseases other than malaria, but it also encourages the emergence and growth of drug resistance through the misuse of antimalarial drugs.

In light of the above, it would therefore be wise to propose an alternative diagnostic approach that would help to better identify cases of severe malaria in children who have a negative microscopy in the context of previous antimalarial drug use.

The best test under these conditions is PCR, but this is not yet available in our country and is rarely used in practice because of its prohibitive cost.

Immunochromatographic tests for malaria, also known as rapid diagnostic tests (RDTs) for malaria, particularly those targeting Plasmodium falciparum, may in our context constitute a reasonable alternative to PCR and a complement to the thick blood smear test (TBS) for diagnosing severe malaria. In addition to their outstanding diagnostic performance, RDTs remain positive for several weeks, even after anti-malarial treatment and parasite clearance. They also have the advantage of being inexpensive, easy to perform and rapid [7] [8] .

We therefore conducted this study with the aim of improving the diagnosis and management of severe malaria in children.

Main Objective:

To study the relevance of malaria RDTs in the diagnosis of severe malaria in children who have started presumptive antimalarial treatment prior to admission.

Secondary Objectives:

Our working hypothesis is that malaria RDTs improve the diagnosis of severe malaria in children who have previously received presumptive antimalarial treatment.

This work is one of the few to have studied the value of RDTs in the diagnosis of severe malaria, with most studies in the medical literature being focused on the diagnosis of the simple form of the disease [9] - [11] . The present study shows that a significant proportion of children hospitalised for severe malaria were still treated presumptively before hospitalisation. Moyen et al. reported a proportion of 35.5% in a study carried out in hospitals in the city of Brazzaville [3] . The abuse of presumptive antimalarial treatment has already been highlighted by other authors [12] - [14] . Presumptive antimalarial treatment for children suspected of malaria has long been the norm in many African countries and is recommended by the WHO [15] . However, in 2010, considering changes in malaria’s epidemiological profile, the availability and effectiveness of diagnostic methods such as RDTs, and the risk of spreading resistance to artemisinin-based combination therapies, the WHO modified its recommendation, stating that “all suspected cases of malaria should be confirmed before treatment is initiated” [6] . This paradigm shift has not always been understood or accepted by all. In our study, parents practising self-medication and paramedical staff were the most likely to continue presumptive treatment, possibly due to being less informed or resistant to change.

Children under 5 years old and those from low socioeconomic households were the majority, a typical profile for children hospitalized with severe malaria [16] [17] . However, in 2015, OKOKO reported a predominance of children over 5 years old, attributing this to better disease prevention in younger children [18] . The same explanation could account for the underrepresentation of children from high socioeconomic households [19] .

Presumptive antimalarial treatment, especially when incomplete, can make it challenging to diagnose malaria by microscopy. Our study confirms this for severe forms of malaria. In fact, in the vast majority (73.2%) of our study population, the diagnosis of severe malaria was uncertain because of the negativity of TBS in the context of previous antimalarial treatment. In this situation, the WHO recommends repeating the TBS 6 to 12 hours later, or performing an RDTs to confirm or exclude the diagnosis of malaria [5] . In our opinion, the 6 - 12 hour delay in repeating the TBS is too long for such a serious pathology, which needs to be treated as an emergency, and the RDTs is the most suitable option because of the rapid delivery of results (15 - 30 minutes) [7] . The use of RDTs in this study helped to better identify cases of severe malaria; the diagnosis of severe malaria was confirmed in 81.7% of cases, compared with 26% before RDT.

From a therapeutic point of view, the prescription of an antimalarial drug for all children before the RDTs, despite a negative TBS result in some, was justified by the diagnostic uncertainty of such a result in a child who had previously received incomplete antimalarial treatment and the seriousness of the clinical picture. However, this approach exposes the child to over-treatment, the risk of drug resistance and delayed diagnosis of other diseases. The introduction of RDTs has had the advantage of improving diagnosis and, as a result, limiting the prescription of antimalarial drugs to malaria-infected children, thereby avoiding the overuse of antimalarial drugs in 13.4% of children.

The diagnostic and therapeutic approach proposed in this study was not associated with increased lethality compared to previous studies; 5.2% versus 26.3% and 6.5% reported by MOYEN and OKOKO, respectively [3] [18] .

The monocentric design of our study makes it difficult to extrapolate our results to all children of Brazzaville. However, as the PICU receives the majority of children presenting with severe malaria, we feel that our results are fairly representative of the situation in children in Brazzaville.

The presumptive use of antimalarial drugs remains common, making it challenging to diagnose severe malaria using microscopy alone. Combining RDT with microscopy enables better identification of cases and appropriate treatment.